Validity of Transdermal Alcohol Monitoring: Fixed and Self‐Regulated Dosing

BACKGROUND: To study the validity of transdermal assessment of alcohol concentration measured by a lightweight, noninvasive device. METHODS: Subjects wore a 227-g anklet that sensed transdermal alcohol concentrations (TACs) every 15 to 30 minutes, downloading results to a remote computer each day. Twenty-four subjects entered a laboratory and received a dose of 0, 0.28, or 0.56 g/kg of ethanol. Breath alcohol concentrations (BrAC) and TAC were measured every 15 to 30 minutes Twenty others [10 alcohol dependent (AD) and 10 not (NAD)] in the community who wore the anklet for 8 days kept a drinking log and provided a BrAC sample each day. RESULTS: In the laboratory, no zero-dose subject, and every subject receiving alcohol, had alcohol-positive TACs. The device distinguished low- and high-alcohol-dosing groups using peak (t14 = 3.37; p < 0.01) and area under the curve (t14 = 3.42; p < 0.01) of TACs. Within dosing groups, average TAC curves were broader (right-shifted) and had lower peaks than average BrAC curves. For community participants, self-reported number of drinks (t18 = -3.77; p < 0.01), area under the TAC curve (t9.5 = -3.56; p < 0.01), and mean TAC (t9.9 = -3.35; p < 0.01) all significantly distinguished the AD and NAD groups. However, individual transdermal readings were not reliably quantitatively equivalent to simultaneously obtained breath results. CONCLUSIONS: Within the limits of the laboratory study, the device consistently detected consumption of approximately 2 standard drinks. On average, the device shows discriminative validity as a semiquantitative measure of alcohol consumption but individual readings often are not equivalent to simultaneous BrACs.